Electrophoretic light scattering (ELS) is the most industrially important and widely used method to determine electrophoretic mobilities of colloidal dispersions that include, but are not limited to, pharmaceutical products, cosmetics, paints, and foodstuffs. However, prior implementations of ELS may not measure with necessary accuracy, precision, and reliability electrophoretic mobilities of some colloidal dispersions including, but not limited to, those with: high ionic strength; low polarity media; low surface charge; and contamination from unwanted particulate matter. The salient features of an apparatus for implementation of ELS are shown in FIG. 1. The salient features of another apparatus for implementation of ELS are shown in FIG. 2. Refer to the description of embodiments provided herein for a detailed explanation of FIG. 1 and FIG. 2. A method is sought that can accurately, precisely, and reliably measure the electrophoretic mobilities of colloidal dispersions that prior implementations of ELS cannot.